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Discussion Starter · #1 ·
So: a couple weeks ago, almost directly following an oil change, I started to notice an unpleasant engine noise from my 54,000 mile Cayman S. Immediately, I feared the worst, assuming that I had an imminent cylinder failure on my hands, or, at best, bore scoring. I talked to a few experts who told me that it sounded bad and that I was likely looking at a replacement engine or a rebuild, but that was only a guess until the internals of the engine could be inspected.

Step 1: was there any metal on your magnetic drain plug? Not at all. Totally clear.

Step 2: send oil sample to Blackstone for analysis. I expected trace elements suggesting a cylinder wall breakdown... but the Blackstone analysis came back TOTALLY clean and perfectly within expected averages for an m97 engine. Hmmm.

Talking with one of the nation's top engine-builders, he tempered the momentary optimism that I felt after getting the Blackstone analysis back: sure, that might *seem* like a good sign, but if there is debris in the oil, it might be larger particles than what the oil analysis would pick up (<30 microns). The next step would be to pull the oil sump pan to check for debris and scope the cylinder walls to check for bore scoring.

I had the car towed to Automobile Associates, one of the northeast's best Porsche specialist shops. They agreed that it sounded like a bad scenario, but not to jump to conclusions yet, as these are noisy engines and there are a lot of things that could produce strange noises.

Meanwhile, I went and complained to everyone I could find about how far Porsche's build quality fell when the company transitioned from the air-cooled era to the m96 986 and 996 cars. IMS bearings, blue paint, D-chunks, cylinder failures, lubrication issues, bore scoring, plastic interiors that squeak and rattle, etc., etc. I mentally prepared myself for either shelling out big bucks for a rebuild or letting the car go as a roller for a song.

WELL... I had my car towed to Automobile Associates on Monday, but it wasn't until yesterday that they were able to take a look at it (there is a lot going on at Lime Rock Park over the next few weekends, so their dance card looks pretty full). Yesterday, when they pulled it into the garage, they heard the sound I described and feared the worst.

They pulled the oil sump pan and found... nothing. Totally clean of any debris or metal shavings.

They checked the magnetic drain plug and spin-on filter (which also has a magnetic strip to trap debris). Nothing. The oil was totally clean.

They scoped the cylinders, and found... nothing. Looked totally fine.

BUT when they went to scope the cylinders, they found that ONE OF THE SPARK PLUGS HAD WORKED ITSELF LOOSE. Sure enough, when they replaced the oil and got the car buttoned up again, the noise that I was hearing had totally disappeared.

Just to make sure, the shop let it idle for awhile and took it on multiple road tests. The car is purring like a kitten. It appears that a spark plug had worked itself loose, and what I was hearing was compression escaping out of the spark plug hole.

SO: I feel a little silly. I mean: how would I have ever guessed that it would be something so simple? I also feel silly for the fact that I'll have to shell out a couple hundred bucks for the analysis, but I guess it's the price one pays for peace of mind. Much ado about nothing. I'm glad that I didn't, like, fly off the handle and offer the roller to the highest bidder or anything. I also maintain my assertion that build quality of these cars is not what they used to be. But it appears (for now) that I have a healthy car with a healthy engine. *KNOCKS ON WOOD*

I checked back in my service records, and it looks like the spark plugs were last changed at 35,000 miles by the shop in PA that sold the car to me (it looks like they did the whole 60,000 mile maintenance at that time). My guess is that it was just torqued *slightly* too loose and worked its way out over the course of 20,000 miles and four years of use? I guess?

So: I'll be picking up the car tomorrow and I'll let you know if the situation changes, but I think the lesson to learn for now is: check all possibilities before jumping to conclusions. AND: If you develop a weird engine noise, before you assume it's an imminent failure... check the torque on those spark plugs.
 

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Interesting. There are many threads on engine noise and someone usually suggests to first check that all the plugs are tight. I have always rolled my eyes as it seems so unlikely, but I guess not. It can be a little challenging to get a torque wrench on all the plugs - maybe some techs get lazy. Be interesting to know if the loose plug was one of the harder ones to get to (furthest forward).
 

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I'll sometimes see sparkplugs lying randomly on the street....

First thing I think of is someone didn't do a good job with the torque wrench...

Just be happy the engine didn't blow the loose plug out... That has been known to mess up the first few threads in the sparkplug hole....
 

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" Meanwhile, I went and complained to everyone I could find about how far Porsche's build quality fell when the company transitioned from the air-cooled era to the m96 986 and 996 cars. IMS bearings, blue paint, D-chunks, cylinder failures, lubrication issues, bore scoring, plastic interiors that squeak and rattle, etc., etc. I mentally prepared myself for either shelling out big bucks for a rebuild or letting the car go as a roller for a song. "

That was a very informative and enjoyable read, thank you for sharing and I am glad it was a lot less severe than what you were thinking. I'm sure all the in between waiting time was stressful.

From a fairly new owner of a 2007 Cayman S I purchased back in April, I particularly like how you listed all the quintessential issues our cars carry, ESPECIALLY, the plastic interiors that squeak and rattle.. lol. My car has just started doing this to a point now where I can hear it a lot louder and more obvious than I remember in the past.

I thought that was funny as I haven't seen that mentioned in other posts I've browsed through since joining here.
 

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Discussion Starter · #5 ·
" Meanwhile, I went and complained to everyone I could find about how far Porsche's build quality fell when the company transitioned from the air-cooled era to the m96 986 and 996 cars. IMS bearings, blue paint, D-chunks, cylinder failures, lubrication issues, bore scoring, plastic interiors that squeak and rattle, etc., etc. I mentally prepared myself for either shelling out big bucks for a rebuild or letting the car go as a roller for a song. "

That was a very informative and enjoyable read, thank you for sharing and I am glad it was a lot less severe than what you were thinking. I'm sure all the in between waiting time was stressful.

From a fairly new owner of a 2007 Cayman S I purchased back in April, I particularly like how you listed all the quintessential issues our cars carry, ESPECIALLY, the plastic interiors that squeak and rattle.. lol. My car has just started doing this to a point now where I can hear it a lot louder and more obvious than I remember in the past.

I thought that was funny as I haven't seen that mentioned in other posts I've browsed through since joining here.
And true to form, right after I got my car back (running well and with a clean bill of health)... the headliner started drooping!
 

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Great outcome and I hope all problems find such an easy solution! Congratulations. On the other side - it is probably good thing you overreacted a little bit and took the problem seriously. Driving around with loose spark plug may cause some very unpleasant problems requiring extensive work.
Some indications that a mechanic will NOT touch any of my cars are: The absence of torque wrench in the vicinity, tightening bolts with an impact wrench and the presence of a hammer around the car.
 
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